Air cooled internal combustion engine with noise reducing means

ABSTRACT

An air-cooled internal combustion engine is provided with noise reducing means without increasing space requirements. A blower is provided to direct cooling air to at least one engine wall, for example a cylinder wall, and an engine accessory such as a fuel tank, which is needed in any event, forms a conduit to convey cooling air away from the engine wall. The cooling air path is lined with noise absorbing material, such as rock wool, held in position by a foraminous sheet. Where the blower impeller is rotatably mounted on a fixed shaft, similar noise reducing means can be provided on the shaft on the downstream side, the upstream side, or both, of the impeller.

1 r Unite States atent 1 1 m1 3,762,497 Hatz et a1. 1 Oct. 2, 1973 AIRCOOLED INTERNAL COMBUSTION 3,601,101 8/1971 Thien et .11 181/33 K x NGWITH NOISE REDUCING MEANS 3,684,053 8/1972 Thicn ct a1 i 181/33 [75]Inventors: Ernst Hatz, Ruhstorf; Johann FOREIGN PATENTS OR APPLICATIONSSchmuck, Feilnbach, both of 761,751

Germany Assignee: Motorenfabrik llatz KG, Ruhstort,

Germany Filed: Apr. 12, 1972 Appl. No.: 243,164

6/1967 Canada 181/33 K Primary ExaminerRichard B. Wilkinson AssistantExaminer-John F. Gonzales Attorney-Roberts B. Larson et a1.

[57] ABSTRACT An air-cooled internal combustion engine is provided withnoise reducing means without increasing space requirements. A blower isprovided to direct cooling air to at least one engine wall, for examplea cylinder wall, and an engine accessory such as a fuel tank, which isneeded in any event, forms a conduit to convey cooling air away from theengine wall. The cooling air path is lined with noise absorbingmaterial, such as rock wool, held in position by a foraminous sheet.Where the blower impeller is rotatably mounted on a fixed shaft, similarnoise reducing means can be provided on the shaft on the downstreamside, the upstream side, or both, of the impeller.

8 Claims, 4 Drawing Figures AlllR COOLEID INTERNAL COMBUSTION ENGTNEWlITH NOISE REDUCING MEANS BACKGROUND OF THE INVENTION The inventionrelates to an internal combustion engine with a cool air blower and withan arrangement for damping the noises occurring.

It has been known to damp noises radiating from the engine elements bycoating, encasing, etc. The walls in the cool air inlet and outlethowever limit the openings that cannot be closed, so that here thedamping or sliencing means can be housed only in a cumbersome andexpensive manner.

It is an object of the present invention to avoid the foregoingdisadvantages and to provide an arrangement for noise reduction whichrequires only a small space and at the same time can be constructed ofvery simple, economically producible elements.

BRIEF SUMMARY OF THE INVENTION The foregoing and other objects whichwill be apparent to those of ordinary skill in the art are achievedaccording to the present invention by disposing the noise absorbingmeans both between the blower and the wall of the engine facing it, forexample a cylinder wall, as well as on the other side of the enginewall. An engine accessory available per se, such as a fuel tank, is usedto form a housing for the noise reducing means on the side of thecylinder remote from the blower. The damping or sliencing meanspreferably comprises a layer made of a soundproofing raw material, forexample rock wool, surrounding the stream of cooling air, and this layeris held on the side of the stream of cooling air in a sieve-likemounting including a foraminous sheet.

In the case of blower having a locally fixed bearing shaft for theimpeller of the blower and with a cylindrical housing surrounding it,according to another embodiment of the invention the sieve-like mountingwith the soundproofing layer is attached on the shaft between theimpeller and the engine wall facing it. In order to enlarge the dampingpath, an additional similar sieve-like mounting with a soundproofinglayer may be additionally attached on the shaft in front of theimpeller.

Another increase of the damping effect will result according to anothercharacteristic of the invention through the fact that a sieve-likemounting with a soundproofing layer also is mounted on the inside wallof the blower housing. in this case the blower housing together with thesieve-like mounting can be supported either by the engine housing or bya sieve-like mounting on the shaft.

In a particularly favorable embodiment of the invention the engine partutilized to convey cooling air away from the engine wall facing away isdeveloped as a fuel tank with a passage for the cooling air. The insidewall of the passage likewise is provided with a soundproofing layer in asieve-like mounting.

DETAIILED DESCRIPTION There follows a detailed description of apreferred embodiment of the invention, together with accompanyingdrawings. However, it is to be understood that the detailed descriptionand accompanying drawings are provided solely for the purpose ofillustrating a preferred embodiment and that the invention is capable ofnumerous modifications and variations apparent to those skilled in theart without departing from the spirit and scope of the invention.

FIG. 1 is a longitudinal schematic section view through an internalcombustion engine and showing noise reducing means in the stream ofcooling air;

FIG. 2 is a cross section view through the fuel tank following lineII-II of FIG. ll;

FIG. 3 is a view like FIG. 1 showing another embodiment of the noisereducing means on the blower; and

FIG. 4 is a view like FIG. 2 showing a different arrangement of noisereducing means in the fuel tank.

FIG. 1 shows a one-cyliner, air cooled internal combustion engine of aknown construction with an engine crank housing 10, a perpendicularcylinder 12 with cooling ribs 12a attached to the periphery as well as acylinder head 14 with horizontal air cooling channels 14a. The cool airblower includes an impeller ll6 with blades 116a attached to theperiphery, and a bearing shaft 18 fixed in cylinder head 14 serves forthe mounting of impeller 16. Blades are surrounded by a cylindricalhousing 20, which is attached to crank housing It) by means of a fewscrews 22. The drive of impeller 16 is accomplished via belt 24 from thecrank shaft which is not shown.

On the side of the internal combustion engine opposite the blower, afuel tank 26 has been attached close to cylinder 12, whereby it is heldon a flange 10a of crank housing 10 by means of screws, which are notshown. Tank 26 has a passage 26a (FIG. 2) for the cooling air which isU-shaped in its cross section. In this manner the cooling air, sucked inby the blower mechanism on the front side of housing 20 and passing theareas of cylinder head 14 as well as cylinder 12 that are to be cooled,can emerge again through opening 26a within tank 26, as the arrows inFIG. ll indicate.

An annular mounting 28 made of sheetmetal is attached to the shaft 18between impeller 16 and cylinder head 14, for example by being forced onthe axle. The connection of the parts of the mountings among oneanother-is accomplished in a suitably known manner, for example, byflanges. Inside mounting 28, a layer 30 of rock wool has been placed asa silencing agent, and the sieve-like surrounding wall 28a makespossible the access to the sound damping agent inside the mounting 28. Asimilar annular mounting 311, 310 with rock wool filling 33 is alsoattached in front of impeller 16 on shaft 18. Finally, a filling 34 madeof rock wool is also provided inside blower housing 20 and is held bymeans of a sieve-like mounting 36.

The exit opening 26a on the opposite side of the cylinder is provided inthe same manner with a layer 38 of rock wool which layer is held inposition by means of a sieve mounting an of a rectangular cross section(FIG. 2) relative to the stream of cooling air. At the same time, thisarrangement is made in such a way that the sound absorbing material 38,4'11) inside tank 26 is invisible from the outside.

It is obvious that as a result of the silencing layer 30 insertedbetween impeller 16 and cylinder head M and the silencing layer 38inside fuel tank 26 and likewise extending up to cylinder 12, thedamping path is considerably enlarged both on the inlet and on theoutlet side of the stream of cooling air without there being anyrequirement for additional space for the damping agents in the engine.The spaces for accessory, which exist in the engine anyway, thus areused in a particularly advantageous manner for the housing of thedamping means, which results in a considerable increase of the dampingeffect with a simultaneous unchanging space requirement of the engine.The damping layers consequently can be inserted not only in the case ofnew engines but they also can be inserted in existing internalcombustion engines or they can be created by replacing the fuel tank.

Since the sieve mountings with rock wool filling do not rotate, thelayering of the damping agent is not disturbed by the centrifugal force.Therefore no unbalancing can occur in the damping agent. Moreover, nocrumbling and gradual loss of the mass occurs under any circumstances inthe fixed damping agent. Finally, the damping layers assure a sufficientannular gap in the blower and therefore in no way affect the stream ofcooling air. The sieve-like mountings therefore can be moved close toadjacent parts (drive belt, impeller) without impeding the degree ofeffectiveness of the blower by these damping agents or undesirable noisedeveloping because of the flow impediment. In the drawing theperforations in the sieve-like mountings have been indicated onlyroughly for reasons of clarity. In reality these mountings however havea large number of perforations, which result in a finely meshed mountingsicvc and thus in easy access to the damping agents.

The arrangement of the silencing agent on the blower also can be madeaccording to FIG. 3 in a modified manner. In this case the blowerhousing 20f is not attached to engine housing but it is carried directlyby the front mounting 31 by way of a few radial ribs 42. The parts 31,and 42 thus are developed in one piece. The wall in this case thusserves merely as a support surface for housing 20' carried by shaft 18.

Let it also be mentioned that the outlet opening 26a inside fuel tank 26could be subdivided in case of need by one or more separating walls inmounting 40 with the same rock wool filling and thus an additionalincrease in silencing could be achieved. In the case of a sufficientwidth of exit opening 26a, naturally the sievelike mounting 40' can bekept open on one side, as FIG. 4 shows.

It will be clear that the engine accessory, such as fuel tank 26, whichis used to form a conduit for conveying cooling air away from the engineis one which is essential to operation of the engine for some otherpurpose. Thus, the engine part has an essential function other than forconveying cooling air and for providing a location for the noisereducing material positioned downstream of the engine.

What is claimed is:

1. In an air-cooled internal combustion engine having blower means formoving an air stream for cooling at least one engine wall and havingmeans for reducing the noises caused by moving engine elements, theimprovement wherein: an engine accessory is utilized to form a coolantair exit conduit for conveying cooling air away from said engine wall;said blower comprises an impeller mounted on a fixed shaft extendingbetween said blower and said engine wall; a layer of noise absorbingmaterial is positioned on said fixed shaft between said impeller andsaid engine wall and surrounding said shaft; and a noise absorbingmaterial is positioned adjacent the cooling air path on the inside ofthe exit conduit formed by said engine accessory.

2. An improved air cooled internal combustion engine according to claim1 wherein said noise absorbing material is in the form of a layersurrounding the cooling air path.

3. An improved air cooled internal combustion engine according to claim1 wherein said noise absorbing material comprises rock wool.

4. An improved air cooled internal combustion engine according to claim1 wherein said noise absorbing material is held in position by mountingmeans comprising a foraminous member.

5. An improved air cooled internal combustion engine according to claim1 wherein a further layer of noise absorbing material is positioned atthe air intake side of said blower on and surrounding said shaft.

6. An improved air cooled internal combustion engine according to claim5 wherein said layer and further layer of noise absorbing material areheld in posi tion by mounting means comprising a foraminous member.

7. An improved air cooled internal combustion engine according to claim1 wherein said blower includes an impeller rotatably mounted within ahousing, wherein said engine includes an engine housing, and whereinsaid blower housing is secured to said engine housing.

8. An improved air cooled internal combustion engine according to claim1 wherein said engine accessory comprises a fuel tank.

1. In an air-cooled internal combustion engine having blower means formoving an air stream for cooling at least one engine wall and havingmeans for reducing the noises caused by moving engine elements, theimprovement wherein: an engine accessory is utilized to form a coolantair exit conduit for conveying cooling air away from said engine wall;said blower comprises an impeller mounted on a fixed shaft extendingbetween said blower and said engine wall; a layer of noise absorbingmaterial is positioned on said fixed shaft between said impeller andsaid engine wall and surrounding said shaft; and a noise absorbingmaterial is positioned adjacent the cooling air path on the inside ofthe exit conduit formed by said engine accessory.
 2. An improved aircooled internal combustion engine according to claim 1 wherein saidnoise absorbing material is in the form of a layer surrounding thecooling air path.
 3. An improved air cooled internal combustion engineaccording to claim 1 wherein said noise absorbing material comprisesrock wool.
 4. An improved air cooled internal combustion engineaccording to claim 1 wherein said noise absorbing material is held inposition by mounting means comprising a foraminous member.
 5. Animproved air cooled internal combustion engine according to claim 1wherein a further layer of noise absorbing material is positioNed at theair intake side of said blower on and surrounding said shaft.
 6. Animproved air cooled internal combustion engine according to claim 5wherein said layer and further layer of noise absorbing material areheld in position by mounting means comprising a foraminous member.
 7. Animproved air cooled internal combustion engine according to claim 1wherein said blower includes an impeller rotatably mounted within ahousing, wherein said engine includes an engine housing, and whereinsaid blower housing is secured to said engine housing.
 8. An improvedair cooled internal combustion engine according to claim 1 wherein saidengine accessory comprises a fuel tank.